1. Field of the Invention
The present invention relates to a sleeve for a printing cylinder comprising a cylindrical support element provided with an external coating of a thermoplastic elastomeric composition (photopolymer) hardenable under the influence of radiation being wrapped around the support element as a sheet and affixed thereto by applying a raised temperature and pressure.
2. Description of Prior Art
Various forms of such a sleeve which is increasingly more frequently used in the printing process, are known from practice. The support element of such a known sleeve usually consists of a thick-walled cylinder which has a sufficient rigidity and to which the photopolymer sheet is fastened and secured by curing. In such a case two problems arise which strongly affect the quality of the printed material produced by means of said sleeve. When manufacturing the cylindrical sleeve pressure is applied so as to cause the photopolymer sheet to be properly secured to the support element. Applying such pressure may then result in rough or uneven areas being formed in the outer surface of the covering sleeve. Such irregularities are to be avoided as effectively as possible.
A second problem occurring with the known sleeves is the presence of air or gas inclusions between the photopolymer sheet and the support element. This likewise causes irregularities to occur in the printed material to be produced so that the quality of the work supplied by a printing machine provided with one or several of such cylindrical sleeves remains below the level desired.